69chevdump,
If you have actually found the highest gear in the transmission, it would be a one to one ratio. The first step to discovering what is really happening would be to jack the rear end up and using the rotation of the tire and drive shaft, determine what your rear end ratio is. This would be the ratio when in HI range. Flip the button to LO while checking, just to see if it shifts to a different ratio.
Hi range figures should be the actual ring/pinion ration. Shifting the axle between the two ranges will verify that the unit works, and that HI range on the button is actually HI range in the rear end...wires haven't been crossed!
Is everything works properly, then several possibilities exist...you haven't found high gear in the transmission, the two speed isn't getting into HI, or the rear end is equipped with a very dramatic ratio.
Jack the rear off the ground and find out what happens where it counts...the rear end.
Stuart
